Nickel-substituted double-perovskites, LnBaCo(1.6)Ni(0.4)O(5+delta) (LnBCN, Ln = Pr, Nd and Sm), are investigated as potential cathode materials for intermediate-temperature solid-oxide fuel cells based on the Ce0.8Sm0.2O1.9 (SDC) electrolyte. The LnBCN materials exhibit high chemical compatibility with the SDC electrolyte at 950 degrees C for 2 h. Substitution of Ni for Co decreases the thermal expansion coefficient and the electrical conductivity, as compared with the nickel-free samples while retaining desirable electrochemical performance. The area-specific resistances of the LnBCN samples on the SDC electrolyte where Ln = Pr, Nd, and Sm at 700 degrees C are 0.056, 0.077, and 0.11 Omega cm(2), respectively. For Ln = Pr, Nd, and Sm cathodes, the maximum power densities of the electrolyte-supported Ni-SDC/SDC/LnBCN single cells with a 0.3 mm thick SDC electrolyte reach 732, 714, and 572 mW cm(-2) at 800 degrees C, respectively. These results show that nickel-substituted LnBCN double-perovskites are potential cathode candidates for use in IT-SOFCs. (C) 2012 Elsevier B.V. All rights reserved.